Properties
| Category | Inosilicates ; Astrophyllite group |
|---|---|
| Formula | (K,Na)3(Fe++,Mn)7Ti2Si8O24(O,OH)7 |
| Crystal system | Triclinic |
| Color | Golden brown to yellow; rarely greenish |
| Crystal habit | Tabular to bladed, radiating, stellate aggregates; lamellar masses |
| Cleavage | Perfect on imperfect on |
| Fracture | Uneven |
| Mohs scale hardness | 3–4 |
| Luster | Greasy, pearly, sub-metallic |
| Streak | Yellowish brown or white |
| Diaphaneity | Translucent to opaque |
| Specific gravity | 3.2–3.4 |
From the Wikipedia article
Astrophyllite is a very rare, brown to golden-yellow hydrous potassium iron titanium silicate mineral. Belonging to the astrophyllite group, astrophyllite may be classed either as an inosilicate, phyllosilicate, or an intermediate between the two. It forms an isomorphous series with kupletskite, to which it is visually identical and often intimately associated. Astrophyllite is of interest primarily to scientists and collectors.
Source
Source record: crystal-compendium/astrophyllite/minerals.json. Fetched from English Wikipedia by the operator 2 October 2026.
https://en.wikipedia.org/wiki/Astrophyllite — revision id 1354094279. Text and properties from Wikipedia, licensed CC BY-SA 4.0.